1. Field of the Invention
This invention relates to systems and methods and methods for systems for providing micro-irrigation, aeration, evacuation and decontamination fluid to a dental hand tool and associated supply lines.
2. Description of the Prior Art
A. Dental Office Equipment
As a patient sits in a dental chair in a dentist's office, the dentist or a hygienist ordinarily cleans the patient's teeth with a variety of picks and brushes. Next, the dentist or a hygienist uses a hand held tool to supply rinse water, a variety of other medicament fluids, air, and vacuum from supply lines to a patient's mouth. U.S. patent application Ser. No. 09/054,277, filed on Apr. 2, 1998, and commonly assigned to the assignee hereof, discloses such a dental handpiece, and more particularly a handpiece that may be used interchangeably as an irrigator, an aerator, an applicator or as an evacuator for treating a patient's mouth.
The air lines in such a handpiece are commonly shared at the air supply with other air operated hand tools used in a dental office at the dentist's or hygienist's disposal. Therefore, the air supply pressure in each dental office is unique to that office because some dentists may operate more or less air tools from the same air supply.
Because of the high costs of high-speed hand tools, these tools are frequently only partially disposable between each patient. The permanent fixtures in a dental office, including the hardware, rinse water supply lines, fluid including air supply lines, and vacuum lines can become conduits for bacterial and disease transmission.
Infection control is a major concern in modern dental offices, with acquired immunodeficiency syndrome (AIDS) bringing this issue to the forefront. The spread of other communicable diseases and bacteria is also an important concern, from transmission of diseases ranging from staphylococcus to the common cold.
Modern dental offices take several precautions to minimize disease and bacterial transmission. First, high-speed hand pieces can be cleaned and decontaminated between each patient. Drills are routinely sterilized between each patient by autoclave, although some dentists only autoclave the equipment once a day or once every several days. Next, the high-speed hand tools and supply lines are designed to avoid retracting contaminated patient materials back into the handpiece (commonly referred to as "suck back") and easily spreading contamination to new patients. Additionally, prophylaxis angles are designed for disposal after each use, or alternatively, the prophy angles should be sealed and autoclaved between each patient. Last, either disposable air-water syringe tips should be placed over the air-water syringe and disposed after each use, or alternatively, the air-water syringe tips should be cleaned and autoclaved between each patient.
B. Dental Unit Water System Contamination
Even with all of these precautions, the liquid, air, and vacuum supply lines to the hand held tool are commonly known to accumulate contaminants that may lead to contaminant introduction into the patient's mouth or the air surrounding the patient's mouth. Collectively, these supply lines are referred to as dental unit waterlines (DUWL) although these lines often carry fluids other than water. The most common cause for DUWL contamination is the production of microbial biofilm on the interior of the lines supplying a high-speed handpiece or the air and fluid lines.
The microbial biofilm problem is exacerbated because pressurized cooling spray is used in the operation of the high-speed handpiece. The pressurization produces aerosols in the field of contamination, increasing the likelihood of microorganism transport through the easily communicable aerosol mechanism. Not only can the aerosol transport mechanism effect later patients through introduction of contaminants from improperly maintained tools, but also can effect the dental personnel subjected to spray within close proximity to the patient's mouth.
Several recent studies have demonstrated that the majority of organisms inhabiting biofilms are nonpathogenic bacteria. However, several additional more dangerous organisms including bacteria from the genera Legionella, Pseudomonas, Mycobacterium, Streptococci and Candida can contaminate the DUWL in unsafe levels, in particular S. mutals, S. salivrius, S. mitis, P. aeruginosa, C. albicans, chloroform, chlorodibromomethane, bromodichloromethane, bromoform, and trihalomethane.
In order to reduce both patient and dental personnel exposure to these harmful contaminants, researchers have identified several antimicrobial rinses for breaking down the biofilm present in the DUWL. These rinses include for example: Listerine.RTM., Dentosept.RTM., Bio2000.RTM., Sodium Fluoride (NaF), chlorhexidine gluconate, Scope.RTM., hydrogen peroxide, and sodium hypochlorite. The rinses are typically used in two different methods. The first method is to flush the system on a regular basis with the rinse and to discard the rinse because the rinse would contain elevated levels of biofilm. The second method is to continuously supply the rinse to the water line during regular dental operation to supply continuous antibacterial application. These compounds are known in the art and used to irrigate, debride and disinfect the mouth of a patient during instrumentation.
These rinses differ in efficacy and if the rinse is used during regular dental operation, some rinses have been shown to break down enamel bond strengths of composites etched to enamel, as is the case with patients having dentures, fillings or caps. Additionally, some rinses have very poor taste if used during regular operation. To date, sodium hypochlorite is the preferred rinse based on efficacy in reducing microbial counts and taste; however, sodium hypochlorite is highly corrosive with respect to metal components common to the dental systems.
Although DUWL decontamination has undergone improvements to reflect a greater understanding of the decontamination procedures necessary, shortcomings still persist. One such shortcoming is the inability to alternately irrigate, aerate, evacuate and decontaminate fluid lines with a single fluid supply system.